Experimental study on combined cooling and heating supply of a transcritical CO2 heat pump based on high-temperature heating optimization

Transcritical CO₂ cycle has great advantages in the combined cooling and heating scenario requiring large heating temperature differences. With the research objective of combined cooling and high-temperature heating (CHH) by the transcritical CO₂ heat pump (TCHP), four parts of the study have been conducted sequentially, focusing on the operational characteristics of the system, the optimization of throttle opening benchmarks, the optimization of controllable parameters and the influence of internal heat exchanger (IHX) on the system. As the result shows: Raising the system heating temperature (T_h) will always reduce its operational performance, and adjusting the compressor speed has a relatively better effect on increasing T_h; A smaller throttle opening can significantly improve the CHH performance of the system, and up to 30.24 % elevation in combined system COP has been reported by optimizing throttle opening benchmarks; The synergistic control strategy of controllable parameters allow the system to achieve optimum operational performance. The optimum combined COP obtained at T_h levels of 80, 90 and 100 °C are 5.193, 4.475 and 3.905, respectively; Introducing IHX has a clear impact on enhancing system performance, with combined COP improvements ranging from 4.25 % to 17.82 % in this study.